ESTÁIS means You are or Are you…? if in a question. Place a simple NO in front –NO ESTÁIS – and there you have: You aren’t or aren’t you? if in a question.

The only difference is, as mentioned above, ESTÁIS is used for addressing more than one person, which is the part that makes it a little tricky for native English speakers, unaccustomed to this difference. But hey…if it were